[Federal Register: November 17, 2003 (Volume 68, Number 221)]
[Rules and Regulations]
[Page 64799-64802]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr17no03-1]
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Rules and Regulations
Federal Register
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[[Page 64799]]
DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 35
[Docket No. NE125; Special Conditions No. 35-003-SC
Special Conditions: Hamilton Sundstrand, Model 54H60-77E
Propeller
AGENCY: Federal Aviation Administration (FAA), DOT.
ACTION: Final special conditions; request for comments.
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SUMMARY: The FAA is issuing special conditions for the Hamilton
Sundstrand model 54H60-77E constant speed propeller. This four-bladed
propeller will have a dual acting digital electro-hydraulic propeller
control system, which is a novel or unusual design feature. The
applicable airworthiness regulations do not contain adequate or
appropriate safety standards for this design feature. These special
conditions contain the additional safety standards that the
Administrator considers necessary to establish a level of safety
equivalent to that established by the existing airworthiness standards.
DATES: The effective date of these special conditions is December 1,
2003. The FAA must receive comments on or before January 30, 2004.
ADDRESSES: Mail or deliver comments on these special conditions to:
Federal Aviation Administration, Office of the Assistant Chief Counsel,
Attention: Rules Docket NE125, 12 New England Executive Park,
Burlington, Massachusetts, 01803-5299. You must identify the docket
number NE125 at the beginning of your comments, and you should submit
two copies of your comments. You may review the public docket
containing comments to these special conditions in person at the Office
of the Regional Counsel between 8 a.m. and 4:30 p.m., Monday through
Friday, except Federal holidays.
FOR FURTHER INFORMATION CONTACT: Jay Turnberg, FAA, Engine and
Propeller Standards Staff, Engine and Propeller Directorate, Aircraft
Certification Service, ANE-110, 12 New England Executive Park,
Burlington, Massachusetts, 01803-5229; telephone (781) 238-7116; fax (781) 238-7199; e-mail: jay.turnberg@faa.gov.
SUPPLEMENTARY INFORMATION:
The FAA has determined that notice and opportunity for prior public
comment hereon are impracticable because these procedures would
significantly delay issuance of the approval design and thus delivery
of the affected aircraft. In addition, the substance of these special
conditions has previously been subject to the public comment process
with no substantive comments received. The FAA therefore finds that
good cause exists for making these special conditions effective on
December 1, 2003.
Comments Invited
The FAA has determined that good cause exists for making these
special conditions effective December 1, 2003; however; the FAA invites
interested parties to submit comments on the special conditions. You
must identify the docket number NE125 at the beginning of your
comments, and you should submit two copies of your comments. The FAA
will consider all comments received by the closing date. The FAA may
change these special conditions in light of the comments received. All
comments submitted will be available in the Rules Docket for
examination by interested persons, both before and after the closing
date for comments. The docket will contain a report summarizing each
substantive public contact with FAA personnel concerning this proposal.
Commenters wishing the FAA to acknowledge receipt of their comments
submitted in response to this notice must include a self-addressed,
stamped postcard on which the following statement is made: ``Comments
to Docket No. NE125.'' The postcard will be dated-stamped and returned
to the commenter.
Background
On February 24, 2003, Hamilton Sundstrand applied for an amendment
to Type Certificate No. P906 to include the new 54H60-77E propeller.
The model 54H60-77E, which is a derivative of the model 54H currently
approved under Type Certificate P906, uses a dual acting digital
electro-hydraulic propeller control system (EPCS).
Digital electronic control introduces potential failures associated
with electrical power, software commands, data, and environmental
effects that can result in hazardous propeller effects. The applicable
airworthiness regulations do not contain adequate or appropriate safety
standards for these design features. These special conditions address
the following airworthiness issues for the Hamilton Sundstrand 54H60-
77E propeller:
1. Safety assessment.
2. Propeller control system.
These special conditions contain the additional safety standards
necessary to establish a level of safety equivalent to that established
by the existing airworthiness standards.
Type Certification Basis
Under the provisions of 14 CFR 21.101, Hamilton Sundstrand must
show that the 54H60-77E meets the applicable provisions of the
regulations incorporated by reference in Type Certificate No. P906 or
the applicable regulations in effect on the date of application for the
change to the model 54H. The regulations incorporated by reference in
the type certificate are commonly referred to as the ``original type
certification basis.'' The regulations incorporated by reference in
P906 are Civil Air Regulation (CAR) part 14, as amended in December 15,
1959.
In addition, if the regulations incorporated by reference do not
provide adequate standards with respect to the change, the applicant
must comply with certain regulations in effect on the date of
application for the change. Hamilton Sundstrand has elected to show
compliance with part 35, as amended through Amendment 7, dated December
28, 1995, for the 54H60-77E.
If the Administrator finds that the applicable airworthiness
regulations (i.e., 14 CFR part 35) do not contain adequate or
appropriate safety standards for the 54H60-77E because of a novel or
unusual design feature, special conditions are prescribed under the
provisions of 14 CFR 21.16.
[[Page 64800]]
As appropriate, special conditions, as defined in Sec. 11.19, are
issued in accordance with Sec. 11.38 and become part of the type
certification basis in accordance with 14 CFR 21.101(b)(2).
Special conditions are initially applicable to the model for which
they are issued. Should the type certificate for that model be amended
later to include any other model that incorporates the same novel or
unusual design feature, or should any other model already included on
the same type certificate be modified to incorporate the same novel or
unusual design feature, the special conditions would also apply to the
other model under the provisions of 14 CFR 21.101(a)(1).
Novel or Unusual Design Features
The 54H60-77E will incorporate the following novel or unusual
design features: dual acting digital electro-hydraulic propeller
control system. Digital electronic control introduces potential
failures associated with electrical power, software commands, data, and
environmental effects that can result in hazardous propeller effects.
The applicable airworthiness regulations do not contain adequate or
appropriate safety standards for these design features. These special
conditions address the following airworthiness issues for the Hamilton
Sundstrand 54H60-77E propeller:
1. Safety assessment.
2. Propeller control system.
These special conditions contain the additional safety standards
necessary to establish a level of safety equivalent to that established
by the existing airworthiness standards.
The existing type certified Hamilton Sundstrand 54H model propeller
as described in FAA Type Certification Data Sheet P906, amendment 7,
uses a mechanical governor in the propeller control system. This
mechanical control system senses propeller speed and adjusts the pitch
by directing hydraulic oil to the propeller actuator to increase or
decrease pitch to maintain the propeller at the correct RPM and to
absorb the engine power.
The Hamilton Sundstrand EPCS replaces the current mechanical
control system with a digital electronic governor in the propeller
control. The digital electronic governor is designed to operate a
hydro-mechanical interface to direct hydraulic oil to the propeller
actuator to increase or decrease pitch. The digital electronic control
logic commands speed governing, synchrophasing, and failure monitoring
and provides beta scheduling. Digital electronic control introduces
potential failures associated with electrical power, software commands,
data, and environmental effects that can result in hazardous propeller
effects.
Safety Assessment
The special conditions require the applicant to conduct a safety
assessment of the propeller in conjunction with the requirements for
evaluating the digital electro-hydraulic control system. A safety
assessment is necessary due to the increased complexity of these
propeller designs and related control systems. The ultimate objective
of the safety assessment requirement is to ensure that the collective
risk from all propeller failure conditions is acceptably low. The basis
is the concept that an acceptable total propeller design risk is
achievable by managing the individual risks to acceptable levels. This
concept emphasizes reducing the risk of an event proportionally with
the severity of the hazard it represents.
The special conditions are written at the propeller level for a
typical aircraft. The typical aircraft may be the aircraft intended for
installation of the propeller. It is advised that the propeller
applicant have an understanding of the intended aircraft, not to show
compliance with this requirement, but to design a propeller that will
be acceptable for the intended aircraft. For example, a part 25
aircraft may require different failure effects and probability of
failure than a part 23 aircraft. Showing compliance with the
requirement without consideration of the intended aircraft may result
in a propeller that cannot be installed on the intended aircraft.
Propeller Control System
Currently, part 35 does not adequately address propellers with
combined mechanical, hydraulic, digital, and electronic control
systems. Propeller mechanical control systems certified under the
existing requirements incorporate a mechanical governor that senses
propeller speed and adjusts the pitch to absorb the engine power to
maintain the propeller at the selected rotational speed. Propellers
with digital electronic control components perform the same basic
function but use software, electronic circuitry, and electro-hydraulic
actuators. The electronic control systems may also incorporate
additional functions such as failure monitoring, synchrophasing, and
beta scheduling. This addition of electronics to the control system may
introduce new failure modes that can result in hazardous propeller
effects.
Applicability
As discussed above, these special conditions apply to the model
54H60-77E propeller. Should Hamilton Sundstrand apply at a later date
for a change to the type certificate to include another model
incorporating the same novel or unusual design feature, the special
conditions would apply to that model as well under the provisions of 14
CFR Sec. 21.101(a)(1).
Conclusion
This action affects only certain novel or unusual design features
on one model of propellers. It is not a rule of general applicability,
and it affects only the applicant who applied to the FAA for approval
of these features on the propeller.
The substance of these special conditions has previously been
subjected to the notice and comment period and has been derived without
substantive change from those previously issued. The FAA has determined
that prior public notice and comment are unnecessary and that good
cause exists for adopting these special conditions immediately.
Therefore, these special conditions are being made effective December
1, 2003. The FAA is, however, requesting comments to allow interested
parties to submit views that may not have been submitted in response to
the prior opportunity for comment described above.
List of Subjects in 14 CFR Part 35
Air transportation, Aircraft, Aviation safety, Safety.
The authority citation for these special conditions is as follows:
Authority: 49 U.S.C. 106(g), 40113, 44701-44702, 44704.
The Special Conditions
Accordingly, pursuant to the authority delegated to me by the
Administrator, the following special conditions are issued as part of
the type certification basis for the Hamilton Sundstrand model 54H60-
77E propeller.
In addition to the requirements of part 35, the following
requirements apply to the propeller.
(a) Definitions. Unless otherwise approved by the Administrator and
documented in the appropriate manuals and certification documents, for
the purpose of these special conditions the following definitions apply
to the propeller:
(1) Propeller. The propeller is defined by the components listed in
the type design.
(2) Propeller system. The propeller system consists of the
propeller plus all
[[Page 64801]]
the components necessary for its functioning, but not necessarily
included in the propeller type design.
(3) Hazardous propeller effects. The following are regarded as
hazardous propeller effects:
(i) A significant overspeed of the propeller.
(ii) The development of excessive drag.
(iii) Thrust in the opposite direction to that commanded by the
pilot.
(iv) A release of the propeller or any major portion of the
propeller.
(v) A failure that results in excessive unbalance.
(vi) The unintended movement of the propeller blades below the
established minimum in-flight low pitch position.
(4) Major propeller effects. The following are regarded as major
propeller effects.
(i) An inability to feather.
(ii) An inability to command a change in propeller pitch.
(iii) A significant uncommanded change in pitch.
(iv) A significant uncontrollable torque or speed fluctuation.
(b) Safety analysis.
(1)(i) Perform an analysis of the propeller system to assess the
likely consequence of all failures that can reasonably be expected to
occur. This analysis must consider the following:
(A) The propeller system in a typical installation. When the
analysis depends on representative components, assumed interfaces, or
assumed installed conditions, the analysis must state the assumptions.
(B) Consequential secondary failures and latent failures.
(C) Multiple failures referred to in paragraph (b)(4) of these
special conditions or that result in hazardous propeller effects.
(ii) Summarize those failures that could result in major propeller
effects or hazardous propeller effects, together with an estimate of
the probability of occurrence of those effects.
(iii) Show that hazardous propeller effects are not predicted to
occur at a rate in excess of that defined as extremely remote
(probability of 10-\7\ or less per propeller flight hour).
As the estimated probability for individual failures may be
insufficiently precise to enable the applicant to assess the total rate
for hazardous propeller effects, compliance may be shown by
demonstrating that the probability of a hazardous propeller effect
arising from any individual failure can be predicted to be not greater
than 10-\8\ per propeller flight hour. Probabilities of this
low order of magnitude may be demonstrated through reliance on
engineering judgment and previous experience combined with sound design
and test philosophies.
(2) The Administrator may, if significant doubt exists, require
testing to verify any assumption as to the effects of failures or
likely combination of failures.
(3) If the primary failure of certain single elements (for example,
blades) cannot be sensibly estimated in numerical terms, and if the
failure of such elements is likely to result in hazardous propeller
effects, then compliance may be shown by meeting the prescribed
integrity requirements of part 35 and these special conditions. The
safety analysis must state these instances.
(4) If reliance is placed on a system or device, such as safety
devices, feathering and overspeed systems, instrumentation, early
warning devices, maintenance checks, and similar equipment or
procedures, to prevent a failure from progressing to hazardous
propeller effects, the analysis must include the possibility of a
safety system failure in combination with a basic propeller failure. If
items of a safety system are outside the control of the propeller
manufacturer, the safety analysis must state assumptions with respect
to the reliability of these parts, and the installation and operation
instructions required under Sec. 35.3 must identify these assumptions.
(5) If the safety analysis depends on one or more of the following
items, the analysis must state and appropriately substantiate those
items.
(i) Performance of mandatory maintenance actions at stated
intervals required for certification and other maintenance actions.
This includes verifying the serviceability of items that could fail in
a latent manner. These maintenance intervals must be published in the
appropriate propeller manuals. Additionally, if errors in maintenance
of the propeller system could lead to hazardous propeller effects, the
appropriate procedures must be published in the appropriate propeller
manuals.
(ii) Verification of the satisfactory functioning of safety or
other devices at pre-flight or other stated periods. The details of
this satisfactory functioning must be published in the appropriate
propeller manuals.
(iii) The provisions of specific instrumentation not otherwise
required.
(iv) A fatigue assessment.
(6) If applicable, the safety analysis must include the assessment
of indicating equipment, manual and automatic controls, governors and
propeller control systems, synchrophasers, synchronizers, and propeller
thrust reversal systems.
(c) Propeller control system. The requirements of this section
apply to any system or component that controls, limits, or monitors
propeller functions.
(1) Design, construct, and validate the propeller control system to
show that:
(i) The propeller control system, operating in normal and
alternative operating modes and transition between operating modes,
performs the intended functions throughout the declared operating
conditions and flight envelope.
(ii) The propeller control system functionality is not adversely
affected by the declared environmental conditions, including
temperature, electromagnetic interference (EMI), high intensity
radiated fields (HIRF) and lightning. Document the environmental limits
to which the system has been satisfactorily validated in the
appropriate propeller manuals.
(iii) A method is provided to indicate that an operating mode
change has occurred if flight crew action is required. In such an
event, provide operating instructions in the appropriate manuals.
(2) Design and construct the propeller control system so that, in
addition to compliance with paragraph (b) of these special conditions,
Safety analysis:
(i) A level of integrity consistent with the intended aircraft is
achieved.
(ii) A single failure or malfunction of electrical or electronic
components in the control system does not cause a hazardous propeller
effect.
(iii) Failures or malfunctions directly affecting the propeller
control system in a typical aircraft, such as structural failures of
attachments to the control, fire, or overheat, do not lead to a
hazardous propeller effect.
(iv) The loss of normal propeller pitch control does not cause a
hazardous propeller effect under the intended operating conditions.
(v) The failure or corruption of data or signals shared across
propellers does not cause a major or hazardous propeller effect.
(3) Design and implement electronic propeller control system
imbedded software by a method approved by the Administrator that is
consistent with the criticality of the performed functions and
minimizes the existence of software errors.
(4) Design and construct the propeller control system so that the
failure or corruption of aircraft-supplied does not result in hazardous
propeller effects.
(5) Design and construct the propeller control system so that the
loss, interruption, or abnormal characteristic
[[Page 64802]]
of aircraft-supplied electrical power does not result in hazardous
propeller effects. Describe the power quality requirements in the
appropriate manuals.
(6) Specify the propeller control system description,
characteristics, and authority, in both normal operation and failure
conditions, and the range of control of other controlled functions, in
the appropriate propeller manuals.
Issued in Burlington, Massachusetts, on November 10, 2003.
Francis A. Favara,
Acting Manager, Engine and Propeller Directorate, Aircraft
Certification Service.
[FR Doc. 03-28676 Filed 11-14-03; 8:45 am]
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